Comment on "Insight of the preponderant role of the lattice size in the Sn-based colusite for promoting high power factor" by P. Kaminska, C. Bourges, R. Chetty, D. Gutierrez-Del-Rio, P. Spiewak, W. Swieszkowski, T. Nishimura, T. Mori, J. Mater. Chem. A, 2022, 10, 10701

The recent paper published by Kaminska et al. (Kaminska et al., J. Mater. Chem. A, 2022, 10, 10701-10714) suggests that the Seebeck coefficient of Sn-based colusites (Cu26T2Sn6S32 with T = V, Nb, Ta) increases with the cell parameter, regardless of the composition/doping or synthesis approach. Multiple lines of evidence disprove this assumption, but are consistent with a composition/disorder effect. This imposes a significant revision of the understanding of the relationship between the structure and thermoelectric properties in this family. Furthermore, the authors claimed to have reached a record power factor (PF) and an increase of 35% compared to state-of-the-art Sn-based colusites. However, a careful comparison with previously published data show that they omitted to consider in their comparison some already published PF values so the peak value achieved remains comparable to the best reported values within experimental uncertainty.